Smoking Quantity and Nicotine Dependence among Young Adults

Introduction

• Psychiatric disorders are a potent group of risk factors consistently implicated in the development of nicotine dependence (Rohde et al., 2003; 2004).
• While the association has been well established in the literature, less is known about the ways in which psychiatric disorders may play a role in the emergence of nicotine dependence.
• Most research has focused on how psychiatric disorders and may be a risk factor for heavy smoking e.g. the self medication hypothesis (Khantzian, 1997).
• Alternately, however, psychiatric disorders may signal a greater sensitivity to nicotine dependence at low levels of smoking (i.e. individuals with psychiatric disorders may develop nicotine dependence symptoms at lower levels of smoking than those without psychiatric disorders).

Research Questions

1. Which psychiatric disorders are associated with nicotine dependence after controlling for comorbidity?
2. Does the association between smoking quantity and nicotine dependence differ for individuals with and without a psychiatric disorders?

Methods

Sample

• Young adults (age 18 to 25) who reported daily smoking in the past year (n=1320) were drawn from the first wave of the National Epidemiologic Study of Alcohol and Related Conditions (NESARC).
• NESARC is a nationally representative sample of non-institutionalized adults in the U.S.

Measures

• Lifetime psychiatric disorders were assessed using the NIAAA, Alcohol Use Disorder and Associated Disabilities Interview Schedule – DSM-IV (AUDADIS-IV).
• The tobacco module includes questions on symptom criteria for DSM-IV nicotine dependence.
• Current smoking was evaluated through quantity (“On the days that you smoked in the last year, about how many cigarettes did you usually smoke?”).

Results

Univariate

• Fully 61% of daily, young adult smokers met criteria for DSM-IV nicotine dependence in the past year.
• A total of 55% met criteria for one or more psychiatric disorders.
• The most common disorder among daily smokers was alcohol dependence (45% SE 1.9).

Bivariate

• Chi-Square analysis showed that daily, young adult smokers with a psychiatric disorder were significantly more likely to meet criteria for nicotine dependence (78.5%) than those without a psychiatric disorder (60.7%), X2=152.3, 1 df, p<.0001.
• As expected, the number of cigarettes smoked per day was significantly associated with DSM-IV nicotine dependence, OR=1.04 (1.03-1.06).

Multivariate

• Major depression (MDD), specific phobia, alcohol dependence, and antisocial personality disorder (ASPD) were each associated with DSM-IV nicotine dependence after controlling for comorbidity.
  The interaction between number of cigarettes smoked per day four specific phobia, ASPD and
• MDD was not found to be significantly associated with the presence of nicotine dependence. At each level of use, the probability of nicotine dependence is significantly higher among those with the disorder than those without (Figure 1).

• In contrast, the interaction between alcohol dependence and number of cigarettes smoked per day was statistically significant when predicting nicotine dependence (Figure 2).
• At lower levels of smoking, individuals with alcohol dependence have substantially elevated rates of nicotine dependence compared to those without alcohol dependence.
• At highest levels of use (30+ cigarettes/day), rates of nicotine dependence are statistically similar for those with and without alcohol dependence.

Discussion

• Individuals with major depression, specific phobia and ASPD may be more sensitive to nicotine dependence across levels of smoking.
• Individuals with alcohol dependence are more sensitive to nicotine dependence at low levels of daily smoking, but not at the highest levels when compared to individuals without alcohol dependence.
• Notably, the present findings are based on cross-sectional data and do not reflect the smoking levels at which nicotine dependence emerges among those with and without psychiatric disorders.
• Further research is needed to determine whether sensitivity to nicotine dependence is based on physical and/or psychological differences related to psychiatric disorders.

References

Khantzian, Edward J. (1997). The self-medication hypothesis of substance use disorders: A reconsideration and recent applications. Harvard Review of Psychiatry. 4(5), 231-244.

Rohde, P., Lewinsohn, P. M., Brown, R. A., Gau, J. M., & Kahler, C. W. (2003). Psychiatric disorders, familial factors and cigarette smoking: I. Associations with smoking initiation. Nicotine & Tobacco Research, 5(1), 85-98

Rohde, P., Kahler, C. W., Lewinsohn, P. M., & Brown, R. A. (2004). Psychiatric disorders, familial factors, and cigarette smoking: II. Associations with progression to daily smoking. Nicotine & Tobacco Research, 6(1), 119-132.